The present invention relates to an airbag fabric which may be self-sealing, self-adhering, and heat welded.
Airbags are used as safety devices in vehicles. Many types of airbags require gas leakage to be minimized when the airbag is inflated. For example, side curtain type airbags are required to remain inflated to protect passengers of a vehicle in a “rollover” type accident. To reduce air permeability of the airbag so that inflation pressure can be sustained, conventional airbags are typically made from an airbag fabric having a coating. A typical airbag is made of a nylon cloth coated with a silicone rubber because the silicone rubber displays good heat resistance and weather resistance properties. Applying the coating to the airbag fabric, however, increases the complexity and duration of the manufacturing process.
Another drawback of conventional silicone rubber coating compositions is that such compositions poorly adhere to a base cloth, such as nylon. To improve adherence, conventional coating compositions typically require a primer, which is applied to the base cloth in advance of the coating. Primers have various disadvantages. For example, application of a primer increases the complexity and duration of the manufacturing process. Additionally, the use of a primer requires the use of organic solvents, which are toxic and may create an aggravated or dangerous working environment. Although attempts have been made to eliminate the need for primers by making silicone rubber coatings self-adhesive, conventional methods have not provided the silicone rubber coating with a sufficient amount of adhesion.
Conventional coating compositions further complicate the manufacturing process because such coatings require a complex curing procedure. The curing procedure typically involves heating the coating to a high temperature to melt the coating, applying the melted coating to a fabric, and allowing the coating to cool, as explained, for example, in U.S. Pat. No. 6,200,915 (incorporated by reference herein). Conventional coating compositions may be formed as a powder. Curing of powder coatings requires heating the powder to a melting point to coat the fabric, as explained, for example, in U.S. Pat. No. 5,928,721 (incorporated by reference herein).